In May, her mother, Laura Bush, gave this answer to a question about gay marriage: "When couples are committed to each other and love each other, that they ought to have, I think, the same sort of rights that everyone has."
John McCain's daughter, Meghan, supports gay marriage, though her father's against it, and the lesbian daughter of former Vice President Dick Cheney supports it too. Gay rights leaders have seized on the generational split as a sign that support for same-sex marriage can come from either party.
"I am Barbara Bush, and I am a New Yorker for marriage equality," the 29-year-old Manhattan resident says in the video on the Human Rights Campaign website. "New York is about fairness and equality. And everyone should have the right to marry the person that they love. Join us."
As president, her father supported a constitutional amendment banning gay marriage.
The gay rights group that made the video plans to show it at a party in New York on Saturday.
"No matter what party they belong to, young Americans believe in basic fairness and equality," Brian Ellner, who is overseeing the Human Rights Campaign's bid for same-sex marriage in New York, told the Times.